Prior art methods for recycling polymeric waste articles, such as post-consumer polymeric bottles, containers and the like, employ a succession of cleaning steps to remove solid and liquid waste residues adhering to the articles. The articles are typically fed to a mechanical granulator exemplified by rotating cutting or chopping blades housed in a chamber enclosure. The blades comminute the articles into particles, or "flakes", as such particles are commonly referred to. The flakes are generally rectangular wafers of about three-eighths of an inch on a side. The granulator chamber may include a water spray composed of a plurality of nozzles mounted in the chamber and oriented to direct the spray to onto the cutting blades during comminution. These types of granulators are commonly referred to as a "wet" granulators to distinguish such from "dry" granulators that do not utilize water sprays or, for that matter, any liquid whatsoever during the granulation process. The nozzles of wet granulators typically receive clean water from a suitable source. In wet granulaters, the water spray obviously also assists ha removing some of the solid and liquid contaminants adhering to the articles. The solid contaminants include paper labels as well as dirt and food particles, whereas liquid contaminants include soap residues and oils. However, oftentimes significant amounts of solid and liquid contaminants are not able to be removed by the clean water spray and thus the flake which is produced by the granulator is not clean enough for use in an injection molding machine. To remove a sufficient amount of the solid and liquid contaminants from the plastic flakes for such usage, the prior art processes typically employ several repetitive steps of washing and rinsing the flakes with clean water following granulation. As will be appreciated, if the number of times the flakes are required to be washed and rinsed during the recycling process could be reduced while nonetheless yielding a sufficiently clean flake for end-use requirements, the recycling process would require less clean water and otherwise be more resource-conserving and efficient.
It is an object of this invention to provide an efficient, natural resource-conserving process and apparatus for converting post-consumer polymeric waste articles into feed stock suitable for recycling.
Another object of this invention is to provide a new and improved process for granulating recyclable containers in a wet granulator system.
Another object is to provide a recycling process wherein post-consumer detergent residues are used to increase the cleaning effectiveness of a wet granulator.
Still another object is to provide an efficient and water-conserving method for processing of post-consumer, high density, polyethylene detergent containers into particulate feed stock for injection molding.
Yet another object is to provide a new and improved wet-granulator in which a detergent of controlled concentration is sprayed into the granulator to enhance cleaning during granulation.